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• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
  • C08L83/04—Polysiloxanes
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
  • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic Table
  • C07F7/02—Silicon compounds
  • C07F7/08—Compounds having one or more C—Si linkages
  • C07F7/0834—Compounds having one or more O-Si linkage
  • C07F7/0838—Compounds with one or more Si-O-Si sequences
  • C07F7/0872—Preparation and treatment thereof
  • C07F7/0874—Reactions involving a bond of the Si-O-Si linkage
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
  • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic Table
  • C07F7/02—Silicon compounds
  • C07F7/08—Compounds having one or more C—Si linkages
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/20—Polysiloxanes containing silicon bound to unsaturated aliphatic groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/48—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule in which at least two but not all the silicon atoms are connected by linkages other than oxygen atoms
  • C08G77/485—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule in which at least two but not all the silicon atoms are connected by linkages other than oxygen atoms containing less than 25 silicon atoms
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/48—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule in which at least two but not all the silicon atoms are connected by linkages other than oxygen atoms
  • C08G77/50—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule in which at least two but not all the silicon atoms are connected by linkages other than oxygen atoms by carbon linkages

Definitions

• the present invention relates to a process for the production of a siloxane monomer mixture and use of said siloxane monomer mixture to produce high molecular weight linear polysilalkylenesiloxanes.
• ring-opening polymerisation with respect to siloxane chemistry relates to a polymerisation process using cyclosiloxane based starting materials.
• the cyclosiloxane based starting materials undergo a polymerisation process involving the ring opening of the cyclosiloxanes by reaction in the presence of a "ring opening
• polymerisation catalyst such as an acid or base.
• An equilibrium between the desired resulting high-molecular compounds and a mixture of cyclic compounds and/or linear oligomers is set up in the course of the polymerisation reaction.
• the resulting equilibrium largely depends on the nature and amount of siloxane(s), the catalyst used and on the reaction temperature.
• Such polymerisation processes are generally carried out in the absence of a solvent, but in the past have been prepared in solvents (e.g. polar and non-polar organic solvents) or in emulsion. However, the use of solvents and/or emulsions are not recommended due to the need for complex processes for their removal after the reaction is complete.
• US5442083 describes a hydrosilylation polymerization process between an Si-H terminated organosiloxane and an unsaturated aliphatic hydrocarbon that contains 2 carbon- carbon double bonds or one carbon-carbon double bond and one carbon-carbon triple bond as an alternate route.
• a method to produce such polymers using silylhydrogen functional intermediates as an alternative to ring opening polymerization of cyclic silethylenesiloxane is described.
• the molecular weight of the resulting products is rather limited
• WO 99/67319 discloses a procedure to obtain high molecular weight silalkylene by ring opening polymerization. However, the number of carbon in the alkyl chain is at least 6.
• Interrante et al describe a method of ring opening polymerization of 1 ,1 ,3,3, 5,5,7,7- Octamethyl-2,6-dioxa-1 ,3,5,7-tetrasilacyclooctane to produce
• Triflic acid trifluoromethane sulfonic acid
• a reasonable yield Polym. Preprints 2001 , 42(1 ), 225.
• Interrante et al. actually appears to produce a high proportion of macrocyclic molecules which aren't suitable for the production of high molecular weight linear polymers sought herein. Interrante et al. were only able to produce polymers with moderate molecular weights up to 30,000.
• US 6,080,829 describes a method to produce cyclic monomers that can be used for the synthesis of the starting molecule used herein. Moreover, in Journal of Inorganic and Organometallic Polymers 1999, 9(1 ), 35-53, Tapsak and al. further describe a method to produce high molecular weight Silalkylenesiloxane containing linear alkyl chains having from 6 to 14 carbon atoms by cationic ring opening polymerization using an ion-exchange resin with good yield. US 6,534,587B1 describes a method to produce copolymers of
• silakylenesiloxane and siloxanes using the above mentioned technique developed by Tapsak.
• a siloxane monomer mixture obtainable by a process comprising the steps of a) ring opening polymerization of a cyclic monomer of the structure
• each R is the same or different and is selected from H, OH, a hydrocarbon group having from 1 to 18 carbon atoms, a substituted hydrocarbon group having from 1 to 18 carbon atoms or a hydrocarbonoxy group having up to 18 carbon atoms and n is an integer between 1 and 6, in the presence of an acidic or basic ring open polymerisation catalyst to form a mixture of siloxane monomers and linear oligomers b) removing the linear oligomers prepared in step (a) optionally using a suitable
• a method for obtaining a siloxane monomer mixture comprising the steps of a) ring opening polymerization of a cyclic monomer of the structure
• each R is the same or different and is selected from H, OH, a hydrocarbon group having from 1 to 18 carbon atoms, a substituted hydrocarbon group having from 1 to 18 carbon atoms or a hydrocarbonoxy group having up to 18 carbon atoms and n is an integer between 1 and 6, in the presence of an acidic or basic ring opening polymerisation catalyst, to form a mixture of siloxane monomers and linear oligomers; b) removing the linear oligomers prepared in step (a) optionally using a suitable
• linear oligomers which are extracted at the end of the ring opening polymerisation reaction, are macrosiloxanes of moderate molecular weight (e.g. a molecular weight of from 20,000 to 45,000g/mol as measured by Triple Detection Size Exclusion Chromatography and calculated on the basis of polystyrene molecular weight standards).
• moderate molecular weight e.g. a molecular weight of from 20,000 to 45,000g/mol as measured by Triple Detection Size Exclusion Chromatography and calculated on the basis of polystyrene molecular weight standards.
• these linear oligomers are in equilibrium with the mixture of siloxane monomers (containing a significant proportion of the cyclic monomer starting material and derivatives thereof).
• linear oligomers which are separated and discarded and the resulting siloxane monomer mixture which is retained and, if appropriate, purified prior to being used in a second ring opening polymerisation reaction as discussed below.
• These linear oligomers or macrosiloxanes would usually be collected as the end product of such ring opening polymer but it has been identified that products of significantly higher molecular weight may be obtained as described herein by the removal of the linear oligomers and the use of the remaining siloxane monomer mixture in a second ring opening polymerisation reaction.
• the cyclic monomer used in accordance with the present invention has the general structure
• X may be the same or different and is selected from
• a linear or branched alkylene group having from 1 to 14 carbon atoms; and an aromatic group having from 6 to 20 carbon atoms.
• each X is a linear or branched alkylene group having from 1 to 6 carbon atoms.
• X is a methylene group or an ethylene group.
• the linear or branched alkylene group may contain a degree of substitution.
• substituted means one or more hydrogen atoms in a hydrocarbon group has been replaced with another substituent.
• substituents include, halogen atoms such as chlorine, fluorine, bromine, and iodine; halogen atom containing groups such as chloromethyl, perfluorobutyl, trifluoroethyl, and nonafluorohexyl; oxygen atoms; oxygen atom containing groups such as (meth)acrylic, carboxyl and polyethers ; nitrogen atoms; nitrogen atom containing groups such as amino- functional groups, amido-functional groups, and cyano-functional groups; sulphur atoms; and sulphur atom containing groups such as mercapto groups.
• halogen atoms such as chlorine, fluorine, bromine, and iodine
• halogen atom containing groups such as chloromethyl, perfluorobutyl, trifluoroethyl, and nonafluorohexyl
• oxygen atoms oxygen atom containing groups such as (meth)acrylic, carboxyl and polyethers
• Each R in the cyclic monomer may be the same or different and is selected from H, OH, a hydrocarbon group having from 1 to 18 carbon atoms, a substituted hydrocarbon group having from 1 to 18 carbon atoms or a hydrocarbonoxy group having up to 18 carbon atoms.
• R is an, optionally substituted, alkyl or alkenyl, group having up to 8 carbon atoms.
• the optionally substituted alkyl group can be, for example, methyl, ethyl, n- propyl, trifluoropropyl, n-butyl, sec-butyl, and tert-butyl.
• the alkenyl group can be, for example, vinyl, allyl, propenyl, and butenyl.
• R may comprise an aryl, alkaryl or aralkyl group having from 6 to 12 carbon atoms.
• the aryl and aralkyl groups can be, for example, phenyl, tolyl, and benzoyl.
• the substituted groups may be as defined above.
• Preferred R groups are alkyl groups having from 1 to 6 carbon atoms, typically methyl and/or ethyl groups.
• n is from 1 to 6.
• n is between 2 and 6 but it is preferred that n has a value of 2, 3 or 4.
• a specific example of cyclic monomer is 1 ,1 ,3,3,5,5,7,7-Octamethyl-2,6-dioxa- 1 ,3,5,7-tetrasilacyclooctane, where X is a methylene group, each R is a methyl group and n is 2.
• the ring opening polymerisation catalyst used in step (a) of the process may comprise one or more suitable basic catalysts.
• alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide or cesium hydroxide, alkali metal alkoxides or complexes of alkali metal hydroxides and an alcohol
• alkali metal silanolates such as potassium silanolate, rubidium silanolate, cesium silanolate, sodium silanolate and lithium silanolate or trimethylpotassium silanolate.
• Other basic ring opening polymerisation catalysts which might be utilised include the catalysts which are the products resulting from the reaction of a tetra-alkyl ammonium hydroxide and a siloxane tetramer.
• the catalyst concentration can be from about 5 ppm to about 500 ppm of Equivalent KOH.
• the KOH equivalence of potassium silanolate ranges from approximately 0.05% to 6.0% KOH by weight.
• potassium silanolate is employed at a KOH concentration of about 20 ppm by weight.
• the ring opening polymerisation catalyst used in step (a) of the process may comprise one or more suitable acidic catalysts. Any suitable acidic ring opening polymerisation catalyst may be utilized as the catalyst. A mixture of such catalysts may alternatively be used.
• acid solutions for example, solutions comprising acetic acid, formic acid, propionic acid, glycolic acid, valeric acid, butyric acid, caproic acid, caprylic acid, capric acid, octanoic acid, lauric acid, myristic acid, stearic acid, palmitic acid, oleic acid, undecylenic acid, Lewis acids, such as BF 3 , AICI 3 , t-BuCI/Et 2 AICI, CI 2 /BCI 3 , AIBr 3 , AIBr 3 .TiCI 4 , l 2 , SnCI 4 , WCIe, AIEt 2 CI, PF 5 , VCI 4 , AIEtCI 2 , BF 3 Et 2 0, PCI 5 , PCI 3 , POCI 3 , TiCI 5 , SbCI 5 ,
• a solution based on dry ice can also be envisaged for the acid solution.
• Strong protonic acids in particular heteropoly acids, perchloric acid, sulfuric acid, hydrochloric acid, HI, HBr, HCI0 4 , H 2 S0 4 , HN0 3 , H 3 P0 4, para-toluenesulfonic acid, trifluoroacetic acid, perfluoroalkenesulfonic acids such as trifluoromethanesulfonic (triflic) acid or esters or salt of strong acids such as Methyl tosylate, methyl triflate and silyl ester trifluoromethane sulfonic acid are preferred catalysts.
• a particularly suitable catalyst for this process is triflic acid.
• X 2 denotes a halogen atom
• M 2 is an element having an electronegativity of from 1 .0 to 2.0 according to Pauling's scale
• R 1 " is an alkyl group having up to 12 carbon atoms
• s has a value of from 1 to 6
• v is the valence or oxidation state of M 2
• t has a value of from 0 to v-1 .
• catalysts suitable for use in the present invention may comprise oxygen-containing chlorophosphazenes containing organosilicon radicals having the following general formula:
• the catalyst may also comprise condensation products of the above and/or tautomers thereof (the catalyst exists in a tautomeric form when Z 1 is a hydroxyl group). All or some of the chlorine atoms can be replaced by radicals Q, in which Q represents the hydroxyl group, monovalent organic radicals, such as alkoxy radicals or aryloxy radicals, halogen atoms other than chlorine, organosilicon radicals and phosphorus-containing radicals.
• the oxygen-containing chlorophosphazenes of formula (I) are preferably those in which no chlorine atom is replaced by a radical Q.
• Numerous phosphazene bases and routes for their synthesis have been described in the literature, for example in Schwesinger et al, Liebigs Ann. 1996, 1055-1081.
• reaction in step (a) may be carried out at any suitable temperature.
• any suitable separation process may be utilized to remove (extract) the oligomeric by-product (i.e. the linear oligomers) at the end of step (a).
• One suitable separation process identified is the introduction of a solvent into the mixture collected at the end of step (a) to precipitate out the oligomer, which can then be easily extracted by filtration or the like, with the solvent added being subsequently removed to leave the siloxane monomer mixture.
• Other separation processes which may be utilised include but are not limited to solvent extraction, size exclusion, ion exchange or liquid chromatography.
• the high molecular weight linear polysilalkylenesiloxanes are typically prepared by subjecting the siloxane monomer mixture to ring opening
• catalysts or mixtures thereof may be utilized but are not preferred.
• a particularly suitable catalyst for this process is, for example, triflic acid.
• X, R and n are as herein before described which process comprises the steps of reacting the aforementioned siloxane monomer mixture, in the presence of the same acidic or basic ring opening polymerisation catalyst as previously mentioned, at a temperature within the melting point range of said mixture.
• X and R are as hereinbefore described, and n is an integer between 1 and 6, in the presence of an acidic or basic ring opening polymerisation catalyst; to form a mixture of siloxane monomers and linear oligomers b) removing the linear oligomers prepared in step (a) optionally using a suitable
• the ring opening polymerisation of the siloxane monomer mixture can take place within a temperature of from about 17°C to 30°C.
• the molecular weight measurements Mn, cyclic dimer (1 ,1 ,3,3,5,5,7,7-Octamethyl-2,6-dioxa-1 ,3,5,7-tetrasilacyclooctane) content and linearity of the polymer were determined by triple detection size exclusion chromatography in tetrahydrofuran solvent (sometimes alternatively referred to as GPC (i.e. gel permeation chromatography).
• GPC i.e. gel permeation chromatography
• a TDA 300-EXD apparatus from Viscotek Corporation was utilised to measure Light scattering, viscosimetry and refractive index as a means of determining Mark Houwink parameters and thereby linearity of the polymer. Samples tested had a
• the cyclic monomer may be prepared via any suitable method of preparation.
• 1 ,1 ,3,3,5,5,7,7-Octamethyl-2,6-dioxa-1 ,3,5,7-tetrasilacyclooctane several routes to its preparation have been described and any of these may be used, but for the sake of completion the 2 step method used for its preparation in this series of examples is depicted below.
• the temperature of the reaction was maintained below 80°C to prevent the formation of tris-chlorosilane or other isomers throughout the duration of the preparation. After 48 hours, 150g of trimethylchlorosilane was collected. After cooling, the reaction mixture was evaporated at room temperature and 20ml of acetone was added into the flask to deactivate the catalyst. The final product was purified by distillation at 63°C under a reduced pressure of 20 mmHg. A purity of about 95% is obtained with a yield of ca. 80%.
• Comparative Example 1 [0038] The process advocated by Interrante et al. was followed in an attempt to produce high molecular weight linear polymers by a series of one step processes for the ring opening polymerization of 1 ,1 ,3,3,5,5,7,7-Octamethyl-2,6-dioxa-1 ,3,5,7-tetrasilacyclooctane using the following process. The polymerization conditions and results are described below in table 1.
• siloxane monomers were purified by distilling the crude mixture to yield a 98% yield of the mixture of siloxane monomers. The purified siloxane monomers were then characterized by proton confirming the presence of the siloxane monomer mixture in accordance with the present invention.
• Example 3 The methanol soluble phase produced in Example 3 was then has been evaporated and purified by distillation to obtain product C, i.e., the unreacted 1 ,1 ,3,3,5,5,7,7-Octamethyl- 2,6-dioxa-1 ,3,5,7-tetrasilacyclooctane.1 g from Example 3, 4 ⁇ of triflic acid was then added, with product C to a three-necked round bottom flask and stirred under argon blanket for 96h at 25°C to lead to product D.
• this process failed to produce high molecular weight polymers as will be seen in Table 2 below. It is thought that this may be because the introduction of the triethylamine into the methanol soluble phase in Example 3 effectively neutralized any remaining acidic species therein such as residual triflic acid.

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